Because hot swapping can generate voltage spikes and data corruption that may damage both the device and the system, avoiding hot swapping is preferable. However, as a user does not have to be concerned about the state of the power supply or I/O bus while adding or removing a device, hot swapping is convenient. Further, the system, having the power supply in the on state, may maintain its tasks while the device is hot swapped.
Hot swapping has been available for devices complying with the Small Computer System Interface (SCSI) standard. However, in many approaches, the device is hot swapped directly from a SCSI bus, which affects all devices attached to the bus. Signal disruption on the bus because of hot swapping may last for many milliseconds. The SCSI specification allows different levels of hot swapping, all of which require that the bus be inactive during hot swapping. If a system supports hot swapping while the bus is active, then the system would have to keep track of all command and data transfers on the bus in order to maintain the system integrity. Unfortunately, there are potentially hundreds or thousands of these transfers during each hot swap.
With the advent of network attached storage (NAS), hot swapping storage devices is more demanding. Further, because some segments of NAS are geared towards small office environment, using SCSI in hot swapping is relatively expensive in such environment.
Based on the foregoing, it is clearly desirable that techniques be provided to solve the above deficiencies.